Four Australian jurisdictions have released public health alerts as infection numbers soar.
The Darling Downs Public Health Unit has become the latest organisation to release a public health alert in response to the current diphtheria outbreak affecting the nation.
In March, the Western Australian Department of Health reported they had been made aware of seven cases of toxigenic diphtheria in Aboriginal people living in the Kimberly region since December 2025, with NT Health issuing its own alert a few weeks later confirming four cases had been identified across Darwin and Alice Springs since 23 March 2026.
South Australia issued a third alert on 10 April after a single case of toxigenic respiratory diphtheria was recorded in a resident in the APY lands. This was the first case of its kind in South Australia since 2021.
The DDPHU reports that more than 80% of cases are cutaneous infections and that First Nations people account for over 90% of recorded cases.
The National Notifiable Disease Surveillance System has recorded over 90 cases of diphtheria to date in 2026, with the bulk of notifications coming from the Northern Territory (57) and Western Australia (34). Both South Australia and Queensland have recorded fewer than five cases.
There were less that 40 cases recorded nationwide in 2025, with no jurisdiction reaching double figures, highlighting the severity of the current outbreak. No state or territory has reported more than 10 cases in a year since 2022, when Queensland recorded 25 cases.
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Diphtheria is caused by toxigenic strains of the Corynebacterium diphtheriae bacteria. Cutaneous infections typically present with primary skin ulcers featuring a grey-white slough or membrane or as a secondary infection of existing skin lesions, while respiratory infections are characterised by fever, a sore throat and malaise before grey-white spots appear on the tonsils or pharynx.
Each public health alert has highlighted the importance of vaccination against diphtheria.
The diphtheria-toxin vaccine is recommended as a routine vaccination in infants, children and adolescents, with routine boosters available for pregnant women, laboratory workers and travellers to countries with limited access to healthcare services.
Further details about diphtheria vaccinations, including which vaccinations are funded under the National Immunisation Program, are available via the Department of Health, Disability and Ageing website.
